If it will take a weld, weld it. It won't be any worse than before and you could get some more life out of it. However, if you don't have access to a welder, you may have trouble finding someone to weld it for you due to the iffy nature of the repair.
For aftermarket mufflers try Wholesale Car Parts (whslparts.com), expressautoparts.com, mbsautoparts.com, importautoparts.com and there are many others. Prices seem to range from $160 to $200.
If you need a cat, you might try Summit Racing as well as others.